1-butyl-1,2-dihydro-6-hydroxy-4-methyl-2-oxonicotinonitrile

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Read across from GLP compliant guideline study (RL1) with supporting substance (structural analogue)

Justification for type of information:

Please refer to section "Additional Information" in the Endpoint Summary for "Read Across Justification".

Reason / purpose for cross-reference:

read-across source

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 372 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 372 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999-05-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

GLP compliance:

yes

Specific details on test material used for the study:

- CAS number: 28141-13-1

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test solution was prepared by direct addition of test substance to the test medium.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Activated sludge from laboratory wastewater plants treating municipal and synthetic sewage. The inoculum was washed, brought to a concentration of 5 g/L dry substance and aerated for 24 hours. 50 mL were added to a total volume of 250 mL to obtain a concentration of 1 g/L dry substance in the test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

30 min

Test temperature:

20 ± 2 °C

pH:

- Before correction: 3.4
- After correction: 7.6
- After 30 min incubation: 8.0

Dissolved oxygen:

- During aeration: >2.5 mg/L
- Immediately before measurement: >6.5 mg/L

Nominal and measured concentrations:

- Nominal concentrations: 0 (control) and 1000 mg/L
- Measured concentrations: no analytics performed.

Details on test conditions:

TEST DESIGN:
- Test vessels: Erlenmeyer-vessels (nominal volume 250 mL)
- Test volume: 250 mL

TEST MEDIUM / WATER PARAMETERS:
- Synthetic medium: 8 mL/vessel 100-fold concentrated OECD Medium

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 372 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

> 372 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Change in oxygen consumption rate compared with the blank control was 0%.

Results with reference substance (positive control):

30-min EC50: ca. 10 mg/L

Validity criteria fulfilled:

yes

Description of key information

Based on data available for the close structural analogue 1-Ethyl-2-hydroxy-3-cyan-4-methylpyridon-6 (CAS 28141-13-1), the 30-min EC50 and EC10 values are >372 mg/L (nominal; based on a.i.) in activated sludge.

Key value for chemical safety assessment

EC50 for microorganisms:

372 mg/L

EC10 or NOEC for microorganisms:

372 mg/L

Additional information

No experimental data on the toxicity to microorganisms are available for the substance itself. Therefore, the microorganisms toxicity potential is assessed based on data available for the close structural analogue 1-Ethyl-2-hydroxy-3-cyan-4-methylpyridon-6 (CAS 28141-13-1). This analogue differs from the substance only in that it has an ethyl- instead of a butyl-chain attached to the nitrogen atom in the pyridine ring.

The toxicity of the close structural analogue 1-Ethyl-2-hydroxy-3-cyan-4-methylpyridon-6 (CAS 28141-13-1) to microorganisms was investigated in an activated sludge respiration inhibition study according to OECD guideline No 209 and in compliance with GLP criteria (BASF AG, 1999). In this limit test activated sludge from laboratory wastewater plants treating municipal and synthetic sewage was exposed to nominal test substance concentrations of 0 (control) and 1000 mg/L (based on test substance) for 30 minutes. Test concentrations were not analytically verified. After the 30 minutes incubation period, the change in oxygen consumption rate compared with the blank control was 0%. Based on these findings, the 30-min EC50 and EC10 values are determined at >372 mg/L (nominal, based on a.i.).

As in the read-across study no effects are observed up to the highest concentration tested, the effect values are not corrected for molecular weight. As the target chemical has a slightly higher molecular weight, this may be considered a worst case approach.